Lightfastness is a term used to describe the permanence of printed images and how well they stand up to exposure to light. Sunlight and artificial lighting can cause a reaction within ink pigments and can cause the color to fade or change over time of exposure. In printing, when an ink is referred to as lightfast, it means the manufacturer states that it has a strong light-fade resistance. There are many techniques to improve the lightfastness of ink pigments. For example, by changing ink chemistry and by utilizing protective overcoats including ultraviolet filters, as well as by using lightfastness additives in the ink, one can improve light-fade resistance. All these approaches have tradeoffs in color strength however, and require additional cost to increase fading resistance.